David macdofald



I UNITED STATES PATENT OFFICE,

DAVID MACDONALD, OF TORONTO, ONTARIO, CANADA, ASSIGNOR TO WILLIAM STONE, OF SAME PLACE.

PROCES S BY WHICH PAPER MAY BE MADE TO ADHERE TO METAL.

SPECIFICATION forming part of Letters Patent No. 357,213, dated February 8, 1887.

' Application filed July 21, 1886. Serial No. 208,661. (No specimens.)

To all whom it may concern? Be it known that 1, DAVID MACDONALD, of the city of Toronto, in the county of York, in the Province of Ontario, Canada, manufacturer, have invented a certain new and useful Process by which Paper may be'Made to Adhereto Metal, ofwhich the following is a specification. V

The object of the invention is to devise a processbywhich paper may be caused to adhere to metal with such persistency that no part of it can be removed without destroying it; and it consists, essentially, in first making the surface of the metal porous by painting it with muriatic or such other acid as may be capable of eating the metal, then coating the surfaceso prepared with the finest varnish, preferably like that commonly used by coach-builders for varnishing carriagegear, and when the coating of varnish has become sufficiently dry that it will not adhere to the finger placed upon it, but is still in a sticky condition, the sheet of paper to be cemented to the'plate is placed on the surface thus prepared, and the metal plate with the paper thus placed upon it is submit-- ted to heavy pressure in a lithographers or other suitable press.

The primary object for which I devised my invention was for the purpose of enabling lithographers to provide metal backs to fancy show-cards or pictures in such a manner that when the picture was once placed upon the surface of the metal it would become permanently attached thereto,and would not peel off,

temperature of the atmosphere.

even when subjected to severe changes in the After considerable experimenting I discovered that by making the surface of the metal plate porous and employing the details of the process substantially in the manner I shall now describe the desired end was secured.

Any suitable acid would probably answer my purpose; but I find that mnriatic acid of full strength with enough zinc added to it to prevent it effervescing by the addition of any more zinc, and when thus killed mixed with an equal quantity of water, produces the desired result when rubbed over the surface of the metal plate. After thus coating the metal plate I prefer-to place it in an oven to facilitate its drying, and when dry I paint it with a coating of fine varnish, preferably that kind of varnish used by coach'builders in painting the gearing of their vehicles. This coating of varnish I permit to dry until it becomes merely sticky. To facilitate this drying, I prefer to place the metal plateinto a japanners kiln, which, if kept at a temperature of about 110 Fahrenheit, will bake the varnish sufficientl y to produce the desired effect in twenty minutes. Ifnot placed in a kiln, I find that it will take about five hours to acquire the desired condition. The sheet of paper at this period should be carefully placed on the surface of this prepared plate, when, by submitting it to heavy pressure in a lithographers or other suitable press,it will be found that the sheet of paper has become so thoroughly amalgamated with the roughened and prepared surface of the plate that it is utterly impossible to peel it off the plate. \Vith the view of finishing or enameling the surface of the paper thus placed on its metal plate, I coat the surface of the paper with a suitable sizing preferably prepared in the following manner: One pound of gelatine glue dissolved in waterwith an ounce of honey prepared produces a suitable elastic sizing for coating the surface of the paper. When this sizing is perfectly dry, I paint the said surface with a coating of the bestEnglish dial-varnish. The platesthus prepared should be placed in racks and allowed to remain for a couple of I days before being used, when it will be found that they can be handled, and the paper with pictures or any ornamentation which may have been printed on itwill be incorporated as perfectly with the metal plate as though the painting had been placed directly on the metal.

What I claim as my invention is 1. The Within-described process of coating metal with paper, consisting in making the metal plate porous, painting the surface thus prepared with a coating of fine varnish, partially drying the same, placing the sheet of paper on the prepared surface, and submitting the same to pressure, substantially in the 2. The within-described process of coating stantially in the manner and for the purpose metal surfaces with paper, which consists in I herein specified. making the metal porous by the application Toronto, July 9, 1886. of a suitable acid paintin the surface thus I T 5 prepared with a eeating of fine varnish, then ID MACDONALD" partially drying the same, then placing the In presence 0f-- sheet of paper 011 the prepared surface, and CHAS. O. BALDWIX, finally submitting the same to pressure, sub- J. M. JACKSON. 

